What are the European emissions standards and why should I care about my car’s standard?

All new vehicles have to meet specific standards for exhaust emissions. The standards have been steadily tightened in the past decade and Euro 6 becomes compulsory for all new cars sold from January 2015. From 2020, owners of almost all existing diesel cars (Euro 1 to 5) face a £10 daily penalty for driving into central London. Other cities are considering similar penalties.

What is the difference between the official test and the real-world test?

The only compulsory test at present is conducted under strictly defined conditions on a rolling road in a laboratory.
The car industry admits that this test does not reflect how vehicles are driven in real life. Manufacturers can adjust their engines to minimise emissions during the tightly defined test cycle, knowing that in the real world drivers will accelerate and brake more frequently and emit more pollutants.

Should I buy a new diesel car to reduce air pollution and avoid paying pollution penalties?

It is unclear whether all cars meeting the Euro 6 standard will be exempt from the £10 penalty planned for central London from 2020.
A spokesman for Boris Johnson, the mayor of London, said that he was working with the European Commission to introduce a tougher testing regime from 2017 "which closely reflects London’s urban driving conditions".
Drivers wanting to be sure of having a less polluting diesel engine that is exempt from the penalties might prefer to await the outcome of negotiations over the new "real world" test.